Method and apparatus for making rubber torsion units



Jlii'le 1944- I J. H. GERSTENMAIER 2,351,329

METHOD AND APPARATUS FOR MAKING RUBBER TORSION UNITS Filed Dec. 12, 1941 2 Sheets-Sheet l LCDCDCDKUQOGC] w l, H H H ii I; {I i; 26 44 ,36 g; l H

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METHOD AND APPARATUS FOR MAKING RUBBER TORSION UNITS Filed Dec. 12, 1941 2 Sheets-Sheet 2 Q O G CYQ Q ark/mu;

Patented June 13,1944

METHOi) AND APPARATUS FOR MAKING RUBBER TGRSION UNITS John H. Gerstenmaier, St. Marys, Ohio, assignor to Wingloot Corporation, Akron, Ohio, a cor-- poration of Delaware Application December 12, 1941, Serial No. 422,694

10 Cla.

This invention relates to methods and apparatus for molding rubber articles, and, more particularly, is Concerned with improved means and methods for vulcanizing rubber torsion units and torsion units having more than two concentric metal sleeves separated by bodies of rubber of different composition and with the rubber vulcanized directly to the metal sleeves.

the like. The foregoing and other objects of my inven- Heretofore, in the manufacture of rubber tortion are achieved by the provision of apparatus sion bushings or torsion units, the rubber genincluding means for supporting a plurality of erally has been extruded and partially cured or laterally spaced, concentrically arranged sleeves, fully cured before being inserted between the remeans for forcing rubber between certain areas spectlve sleeves of the bushings. Sometimes the of the sleeves, and means for vulcanizlng the rubrubber has been vulcanized to one sleeve and her in position between the sleeves. More parmade of a greater outside diameter than the larly, t apparatus of y i v n n y i other sleeves, and then the inner sleeve has been clllde se d means for forcing ot e d forced into the outer sleeve t compress the rubof rubber between other areas of the sleeves, and, ber therebetween, leaving an unbonded relation sp ifi ally, a old, a r rem va ly car i d at between the bushing and the outer sleeve. A the center of the mold, & p un er slidably r ie rubber torsion unit or bushing made in this many e core. a second plunger slidably c ed b ner is subject to slippage between the rubber and tween the first-named plunger and the mold, and the metal sleeves when carrying a high torque with the mold and core being f ed h reload. Also, it has been found that the methods so 095885 nd receiving separate bodies of rubber. described have resulted in air pockets which pre- The method of my invention includes the step vent meient a d complete ntact f the bb r of positioning an outer metal sleeve-concentric to with the metal sleeves. an inner metal sleeve, positioning at least one The same disadvantages have been experienced metal sleeve f in ermediate diameter and greatin connection with those bushings or torsion so er length than the first-named sleeves between units in which rubber rings are first formed nd the first-named sleeves and so that the intermepartially or wholly vulcanized and then forced diate sl nds l tudinally y nd th into the space between the sleeves. The difilculfirst-named v e aging a bo y of r er ties mentioned are further complicated during against the inne surface of the intermediate the manufacture of a rubber torsion unit 'comsleeve, en agin a y of rubber against h prising m re than on body of rubb r, for examouter surface of the intermediate sleeve, forcing ple, a torsion unit including three concentric the rubber bodies under heat an P ure t metal sleeves with the inner and the intermediate positions between and in engagement with the sleeves being separated by rubber having a diner several sleeves, ins the rubber bodies to ent degree of hardness from the rubber separatthe sleeves, and cutting ofl that portion of the ing the intermediate and the outer metal sleeve. intermediate sleeve extending longitu y It is the general object of my invention to avoid y nd t e inner and outer Sleevesand overcome the foregoing and other dimculties For a bet r understanding of my nventi n of and objections to prior known methods and reference Should be d t e a o panyin apparatus by the provision of improved means drawings. wherein: and methods for vulcanizing rubber torsion units i 1 is a vertical. r ss-s t n l Vi w t rou h or bushings. a mold assembly in the initial position and incor- Another object of my invention is the provision porating the principles of my invention and takof an improved, relatively-inexpensive, easilyen substantially on line I--I of Fig. 3; operated apparatus for vulcanizing rubber tor- Fig. 2 is aview similar to Fig. l, but illustrating sion units,,and particularly torsion units having the mold assembly in the closed or vulcanizing a plurality of kinds of rubber therein and with position; the pp r fun i ning to vulcanize the rub- Fig. 3 is a plan view of the base of the mold ber directly to the metal sleeves. assembly; and

Another object of my invention is to provide a Fig. 4 is a diametrical cross-sectional view of a rapid, easily-performed, relatively-inexpensive rubber torsion unit constructed with the apmethod for facilitating the molding and vulcaniparatus and by the method of my invention. zation of rubber torsion units and the like. Referring to Figs; 1, 2 and 3 of the drawings,

Another object of my invention is the provithe numeral Ill indicates generally a mold havsion of an improved method for making rubber ing an opening or recess l2 adapted to receive ing operations.

plunger 56 is conveniently'made in a plurality of parts, and this usually takes the form of two parts formed by. a diametric split of the plunger.

The mold I is provided with a base l6 which is generally made removable from the mold ill, but which can be quickly aligned with the mold, as, for example, by the provision of a plurality of dowel pins l8 secured to the base I 6 at circumferentially spaced points, and received within recesses 20 formed in the bottom of the mold III.

The base I6 is generally provided with concentrically positioned annular ribs 22 and ,24, with the rib 24 engaging with the inner periphery of the end of the outer metal sleeve l4 to still further align the sleeve and the mold assembly together. The inside rib 22 is spaced radially inwardly from the outer rib 24 so as to form a. groove between the ribs, which groove is adapted to receive and position an intermediate metal sleeve, indicated by the numeral 26. The intermediate metal sleeve 26 is positioned concentrically of the outer metal sleeve l4, but is spaced laterally therefrom in the manner clearly illustrated in the drawings. The base l6 of the mold assembly may also be formed with clearance spaces 30 into which surplus rubber may flow from the mold cavity, and to facilitate this flow of rubber, small grooves or other clearance spaces (not shown) may be provided between the bottom of the mold l0 and the upper surface or the base l6. 1

Mounted, generally in a removable manner at the center of the base I6, is a core member 34 which is adapted to removably receive and closely support an inner metal sleeve 36 forming a. part of the torsion unit. The core member 34 may be releasably mounted on the base l6 by the provision of a dowel pin 38 on the base which is received within a complementary recess 40 formed at the lower end of the core member. The upper end of the core member 34 is reduced in diameter so as to provide a recess which is adapted to receive a body of rubber 44, with the body being positioned between the intermediate metal sleeve 26 and the reduced portion of the core member 34. Slidably mounted onthe reduced portion of the core member 34 is a plunger 46 which is of an over-all diameter which will permit it to slide closely within the intermediate sleeve 26. A rib 48 may be formed upon the bottom outer periphery of the plunger 46, which rib is similar to the rib 22 and which is adapted to cooperate therewith to form concavities in the end of the rubber body positioned between the inner sleeve 36 and the intermediate sleeve 26 during the vulcanizing operation, and in the manner illustrated in Fig. 2 of the drawings.

The mold member Ill is provided with a recessed portion 50 which is adapted to receive a body of rubber 52, with the rubber engaging with the outer periphery of the intermediate sleeve 26. Slidably positioned between the mold l0 and the plunger 46 is a second plunger 56 which is formed with a counterbore 58 adapted to receive the upper end of the intermediate sleeve 26. An annular rib 60 may be provided upon the inner periphery of the bottom of the plunger 56, which rib cooperates with the rib 24 to form concavities in the ends of the rubber body vulcanized between the intermediate sleeve 26 and the outer sleeve l4, and in the manner illustrated in Fig. 2 of the drawings. The second From the drawings it will be seen that the intermediate sleeve 26 is of considerably greater length than the sleeves l4 and 36, and extends longitudinally above the inner and outer sleeves in the manner clearly illustrated in the drawings. This use of an intermediate sleeve of extra length facilitates, in the combination of parts described, th use-of rubbers of different degree of stifiness in the torsion unit. For example, the rubber body 44 may be of a composition having quite different spring characteristics than the rubber body 52, so that in the torsion unit produced one of the rubber bodies will absorb all primary stresses, both in torsion or in radial thrust, and the second rubber body will not come into play until the unit or Ibushing is sub .lected to considerably higher stresses.

In the use of the apparatus, and in accordance with the practice of the method of my invention, the various parts of the mold assembly are assembled together in the relation shown in Fig. 1 of the drawings, and usually bodies of rubber of different characteristics are positioned to the inside and to the outside of the intermediate sleeve 26. Th rubber bodies ordinarily are made up from a plurality of layers of rubber wound to ring-shape and cut into short. lengths, or the rubber bodies may be made up from an extruded section of rubber cut to proper length, formed into a circle and butt-spliced together at the ends. The metal sleeves I4, 26 and 36 are generally madeof steel or other metal and are suitably brass-plated and cemented to facilitate the direct and positive vulcanization of the rubber bodies thereto. Usually, the inner periphery of the inner metal sleeve 36 is appropriately corrugated, grooved, or ribbed to facilitate the attachment of a shaft or other member thereto. and the outer periphery of the outer sleeve l4 may be similarly formed for the attachment of a housing thereto.

With the parts in the assembled relation shown in Fig. 1 of the drawings, the mold assembly is positioned between the platens ID and 12 of a press, and the platens may be appropriately recessed for the reception of heating fluid such as steam. The platens are then moved together under pressure and move the plungers '46 and 56 down into high-pressure relationship with the rubber bodies 44 and 52 to force the rubber bodies down between the several sleeves. The flow of the rubber bodies is facilitated by the application of heat through the mold assembly from the platens, or the heat may be supplied in other ways, as, for example, by placing the mold assembliesin a pot heater, steam jacket, or by appropriately recessing the wall of the mold ID if suillcient heat is not obtained from the platens, and all in a manner that will be well understood by those skilled in the art. The movement together of the platens I0 and 72 is continued until the mold assembly takes the position shown in Fig. 2, after which further movement together of the platens is prevented. The

continued application of heat to the assembly and in the position shown in Fig. 2 causes the rubber of the several bodies to be vulcanized in very positive engagement between the various sleeves, and any excess of rubber flows out through the clearances 30.

After the vulcanizing operation the platens are moved apart and the mold assembly is reassua e stripping out the core member 34 through the suitable opening it in the top of the plunger 56, followed by the stripping of the inner plunger 36 and the stripping of the mold Ill.

The finished torsion unit is illustrated in Fig. 4 and includes the inner metal sleeve 36, the intermediate metal sleeve 26 with the interposed body of rubber N vulcanized to and between the sleeves, the outer metal sleeve Hi and the body of rubber 52 vulcanized to and between the outer metal sleeve and the intermediate sleeve. The longitudinal extension of the intermediate sleeve 26, illustrated in dotted lines in Fig. 4, is cut ofi after the vulcanizing operation so that the intermediate sleev has a length substantially equal to the length of the remaining sleeves of the assembly.

From the foregoing ,it will be recognized that the various objects of my invention have been achieved by the provision of a relatively simple method and apparatus for facilitating the vulcanization oi torsion units, bushings, and the like. The apparatus and method can be operated and performed by the ordinary workman to produce rapidly, emciently and in full scale production practices, a rubber torsion unit having the several rubber bodies directly and positively vulcanized to the plurality of metal sleeves without the trapping of air.

While, in accordance with the patent statutes, I have specifically illustrated and described my invention, it should be understood that I am not to be limited thereto or thereby. but that the scope of my invention is defined in the appended claims.

What I claim is:

1. Apparatus for making rubber torsion units, and the like, and including means for supporting a plurality of laterally spaced, concentrically arranged sleeves, means for receiving one kind of arranged sleeves, means for forcing one kind of rubber from a position remote to a position between two of the sleeves, and a second means for forcing another kind of rubber from a position remote to a position between one of the lastmentioned sleeves and another of the sleeves, and means for vulcanlzing the rubber in position between the sleeves.

3. A mold for vulcanizing a rubber torsion unit, and the like, and comprising means for surrounding and supporting a relatively short outer metal sleeve, means for interiorly supporting an inner metal sleeve of substantially the same length as the outer metal sleeve and concentric to the outer sleeve, means for positioning a longer sleeve of a diameter substantially intermediate of the inner and outer sleeves between the inner and outer sleeves and concentric thereof and spaced therefrom, means for forcing a body oi rubber be tween the inner sleeve and the intermediate sleeve, and means for forcing a second body of rubber between the intermediate sleeve and the outer sleeve.

4. A mold for vulcanizing a rubber torsion unit,

' and the like, and comprising means for surrounding and supporting a relatively short outer metal sleeve, means ior supporting an inner metal sleeve .of substantially the same length as the outer metal sleeve and concentric to the outer sleeve, means for positioning a sleeve of a diameter substantially'intermediate of the inner and outer sleeves between the inner and outer sleeves and concentric thereof, and means for forcing rubber between the inner sleeve and the intermediate sleeve, and separate means for forcing rub sleeve of a bushing, a plunger slidably carried by the core, a second plunger slidably carried between the first-named plunger and the mold, at least one of said plungers having a recess for slidably receiving an intermediate sleeve, and said base being adapted to engage the other end of the intermediate sleeve, said mold being formed with a recess for receiving a body of rubber adapted to be operated on by the said second plun er, and the core being formed with a recess for receiving a body of rubber adapted to be operated on by the first-named plunger.

6. Apparatus for making rubber torsion bushings, and the like, and comprising a mold having an opening receiving and supporting the outer metal sleeve of a bushing, a core carried at the center of the mold and adapted to support conouter metal sleeve of a bushing, a base mounting the mold, a core carried at the center of the mold by the base and adapted to support concentrically oi the outer sleeve an inner metal sleeve of a bushing, a pair of plungers slidably associated with the core and mold, said plungers having a clearance for slldably receiving one end oi an intermediate sleeve, said base being adapted to en,- gage the other end of the intermediate sleeve, said mold being harmed with a recess for receiving a body of rubber adapted to be operated on by one of said plungers, and the core being formed with a recess for receiving a body of rubber adapted to be operated on by the other of said plungers.

8. That method oi making rubber torsion bushings, and the like, which comprises positioning an outer metal sleeve around an inner metal sleeve and in spaced relation therefrom, positioning at least one metal sleeve of intermediate diameter and greater length than the first-named sleeves between the first-named sleeves and so that the intermediate sleeve extends longitudinally beber bodies under heat and pressure to positions between and in engagement with the several sleeves, vulcanizing the rubber bodies under heat and pressure to the sleeves, and cuttingpif that portion of the intermediate sleeve extending longitudinally beyond the inner and outer sleeves.

9. That method of making rubber torsion bush- 4 lugs, and the like, which comprises positioning an outer metal sleeve around an inner metal sleeve and in spaced relation therefrom, positioning at least one metal sleeve of intermediate diameter and greater length than the first-named sleeves between the first-named sleeves and so that the intermediate sleeve extends longitudinally beyond the first-named sleeves, forcing rubher under heat and pressure from a remote position to a position between and in engagement with the several sleeves, vulcanizing the rubber under heat and pressure to the sleeves, and cutting on that portion or the intermediate sleeve extending longitudinally beyond the inner and outer sleeves.

10. That method of making rubber torsion bushings, and the like, which comprises positioning at least one metal sleeve of difierent diameter and greater length concentricto another sleeve and so that the longer sleeve extends longitudinally beyond the other sleeve, engaging a body of rubber against a surface of the longer sleeve extending beyond the shorter sleeve, forcing the rubber body under heat and pressure to a position between and in engagement with the sleeves, vulcanizing the rubber body under heat and pressure to the sleeves, and cutting on? that portion of the longer sleeve extending longitudinally beyond the shorter sleeve. I

JOHN H. GERSTENMAIER. 

